Vacuum crushing and grinding of laboratory samples is performed in a sealed environment free of oxygen, moisture and dust to prevent sample oxidation, moisture absorption and contamination. It is especially suitable for environmentally sensitive materials, such as easily oxidizable metal powders, thermosensitive biomaterials, moisture-prone pharmaceutical samples and more. Below are the operational methods and key precautions for vacuum grinding.

1. Core Principle

Combine vacuum or inert atmosphere control systems with crushing and grinding equipment. Two mainstream solutions are commonly adopted in laboratories:

1. Integrated vacuum grinding equipment: professional machines with built-in vacuum and atmosphere regulation functions.
2. Vacuum glove box combined with conventional grinding instruments: place small grinding devices inside a vacuum glove box to complete the whole process under inert atmosphere.

2. Detailed Operational Procedures

Solution 1: Integrated Vacuum Grinding Equipment (e.g. Vacuum Planetary Ball Mill)

1. Sample preparation: Load test samples into vacuum grinding jars (agate jars, stainless steel jars, etc.) and add matched grinding balls.
2. Vacuuming and inert gas filling: Seal the grinding jars and connect them to the vacuum system. Evacuate to the target vacuum degree (generally below 10 Pa), then fill with argon or nitrogen to slight positive pressure. Repeat the process 2 to 3 times to fully eliminate residual air.
3. Parameter setting: Set rotational speed, grinding duration and forward-reverse rotation mode according to sample properties. For planetary ball mills, the common speed ranges from 200 to 600 rpm with a grinding time of 10 to 60 minutes.
4. Grinding operation: Maintain a stable vacuum or inert atmosphere during equipment operation. Cool the jars to room temperature before opening and collecting samples after grinding.

Solution 2: Vacuum Glove Box Equipped with Conventional Grinding Devices

1. Glove box pre-treatment: Evacuate the glove box and fill it with inert gas (argon or nitrogen) in cycles for three times. Control the internal oxygen content below 100 ppm and water content below 50 ppm.
2. Loading equipment and samples: Transfer small grinding instruments, grinding jars, raw samples and grinding balls into the glove box through the transition chamber.
3. In-box operation: Complete sample loading and jar sealing inside the glove box, then start the grinding machine. The entire grinding process is conducted under isolated inert atmosphere.
4. Sample collection: After grinding, open the grinding jars inside the glove box and seal the processed samples for storage immediately.

3. Key Precautions

1. Sample pre-treatment: Pre-freeze samples with volatile components by liquid nitrogen to avoid component volatilization and cross contamination during grinding.
2. Sealing guarantee: Adopt grinding jars equipped with vacuum sealing valves for airtight performance; ensure tight sealing of the glove box transition chamber.
3. Safety protection: Control grinding speed to reduce friction heat when handling flammable and explosive samples. Wear protective goggles and gloves throughout the operation.
4. Post-processing: Subpackage and seal ground samples under inert atmosphere to isolate ambient air.

In summary, laboratory vacuum crushing and grinding is realized by integrated vacuum grinding machines or vacuum glove boxes paired with conventional grinding tools. The core requirement is to sustain an oxygen-free and moisture-free sealed environment. Standard procedures include sample preparation, atmosphere adjustment, parameter configuration, sample collection and sealed preservation. Strict attention shall be paid to airtightness, operational safety and sample stability throughout the experiment. Compared with ordinary grinding, vacuum grinding involves more safety specifications and requires careful standardized operation.